The present invention is directed to an arrangement for calculating the fuel injection quantity for an internal combustion engine.
A control device calculates the fuel injection quantity for the internal combustion engine for output, signals for the mass stream of air taken in and for the speed of the internal combustion engine. However, an air mass meter having a heated sensor outputs an output signal which is a function of the mass stream of air taken in during steady state operation, i.e. when its heated sensor is heated to operating temperature. This, however, is not the case when starting the internal combustion engine. The measuring circuit does not distinguish between the current conduction for heating the heated sensor and current conduction caused by a mass stream of air. Accordingly, an output signal results that corresponds to too great an air mass value.
European Pat. No. 0 064 664 discloses a device in which the output signal of the air mass meter is supressed during the starting procedure of the internal combustion engine until the expiration of a timer and that a replacement signal be used instead. The error caused by the heating current thereby has no effect.
Tests, however, have shown that a further error in the output signal of the air mass meter occurs for a warm start of the internal combustion engine This error also leads to erroneously elevated air mass values and is slow to decay.
The present invention relates in particular to an arrangement having an air mass meter, that has a bridge circuit having a heated sensor and an air temperature sensor in an intake train of the internal combustion engine. The air mass meter further has a measuring circuit and a power supply for the bridge circuit, that outputs an output signal dependent on the mass stream air taken in. Also a tachometer outputs an output signal dependent on the rpm of the internal combustion engine. A control device using the output signals of the air mass meter and of the tachometer, calculates the fuel injection quantity to be supplied to the internal combustion engine. An ignition switch for switching the arrangement on and off is also provided.